U.S. Pat. No. 2,651,619, Sept. 8, 1953 (de Mello et al) discloses the stabilization of soils, such as the top layer of a roadway, by mixing therewith a water-soluble polyvalent metal acrylate, such as calcium acrylate, and polymerizing the acrylate with a redox catalyst system. Using 4 to 25%, based on dry soil weight of calcium acrylate, compressive strengths of the stabilized soil up to 600 psi are obtainable.
Morgan et al U.S. Pat. No. 2,801,984, Aug. 6, 1957 discloses compositions for stabilization and impermeabilization of soils with a water-soluble copolymerizable mixture of an alkylidene bisacrylamide, particularly N,N'-methylene bisacrylamide, with a relatively large proportion of one or more water-soluble ethylenic monomers. The latter monomer is broadly defined in the passages of column 2, lines 59-71, and from column 8, line 50, to column 9, line 13. The extensive list of specific monomers presented in column 9, lines 14 to 71 includes alkaline earth metal as well as alkali metal acrylates and methacrylates. However, in lines 16-18 of this passage, N-methylol-acrylamide, calcium acrylate, and methacrylamide are especially mentioned as examples and it is asserted that optimum results are obtained with acrylamide. In the actual working examples, acrylamide, N-methylol acrylamide, and calcium acrylate, or mixtures of two or more of them are used.
Roth U.S. Pat. No. 2,801,985 Aug. 6, 1957 is similar to Morgan et al in respect to the definition of the covalent crosslinker and that of the water-soluble ethylenic comonomer but is based on the use of nitrilotrispropionamide (NTP) as the activator (or accelerator) of a redox system. All working examples use a mixture of acrylamide and N,N'-methylene bisacrylamide, in most of which the polymerizable mixture comprises 95% of acrylamide and 5% of the bisacrylamide which is designated in the patent as "Stabilizer AM-955" and like AM-9 and "AM-9 PLUS", is a registered trademark of American Cyanamid Co. for mixtures of acrylamide and N,N'-methylene bisacrylamide.
Davis et al, U.S. Pat. No. 2,842,338, July 8, 1958 points out that many factors are involved when calcium acrylate is used in attempts to impermeabilize soils and permeable formations penetrated by wells making it difficult to control. Davis et al provides systems for plugging such permeable formations wherein polyacrylic acid is first introduced into the formation through the drilling fluid, and then a water-soluble salt of a polyvalent cation, such as calcium or magnesium chloride, is introduced to react with the acrylic acid polymer and cross-link it.
Ramos et al U.S. Pat. No. 3,136,360, June 9, 1964 discloses the addition of a "filter aid material", such as diatomaceous earth, to gel-forming sealing compositions such as the AM-9 compositions of Roth supra for use for sealing-off an underground water-bearing formation penetrated by the bore of a well in which air or gas drilling operations are being performed. Clarke, U.S. Pat. No. 4,094,150, June 13, 1978, incorporates an unfired natural diatomaceous earth, 80% having a particle size between about 2 and 10 microns, in an acrylamide/N,N'-methylene bisacrylamide grout of the AM-9 category.
Higashimura et al, U.S. Pat. No. 3,580,879 May 25, 1971 discloses grouting with gelable compositions which may comprise (1) 1 to 90 weight % of a metal (meth)acrylate (2) 3 to 90 weight % of a water-soluble ethenoid monomer, such as acrylamide or a hydroxyalkyl or an aminoalkyl (meth)acrylate, and (3) 1 to 30 weight % of a water soluble divinyl monomer. The metal of (1) may be monovalent to polyvalent (column 3, line 72 to column 4, line 7); the monomer of (2) may be acrylamide or any of those mentioned in column 3, lines 40-53; and the divinyl monomers may be any of those listed in the passage of column 3, lines 61-8. However, the gist of the patent is the use of certain redox catalyst systems for accelerating the polymerization.
American Cyanamid Company bulletin ENT-15 having 8 pages and published in 1977 illustrates on page 5 thereof typical "mixing packer" grouting equipment of conventional construction for grouting leaky joints or cracks in a sewer line or conduit. The AM-9, AM-955, and AM-9 PLUS grouts have had extensive commercial application for the grouting of sewer lines or other conduits using this type of equipment. This grout which contains a large proportion of acrylamide (a neurotoxic chemical) is a serious health hazard and, as stated on pages 6, 7, and 8 of this bulletin (ENT-15), requires special core, clothing, and so on. Other American Cyanamid Company bulletins on grouting sewer lines with AM-9 or AM-9 PLUS that show this type of equipment include EN-115 (1975), especially pages 1-5 thereof; EN-111A (1975), page 2; and the 95 page booklet EN-4 (1975) page 26 especially. Attempts heretofore to provide effective chemical grouts adapted to be applied in sewer lines by conventional equipment without acrylamide content by using calcium or magnesium acrylate or methacrylate have previously been unsuccessful for one or more of various reasons: too much shrinkage by loss of water on setting of the polymer gel; too strong a polymer gel making it difficult or impractical to move the "packer unit" to the next grouting position within the line; too long a gel time--about 10 to 30 seconds gel time is required for efficient sealing of sewer joints; too high viscosity--in practice, a low viscosity (about 5 to 10 cps) grout is required to seal the joint and to penetrate the soil around the joint.